Chinese hackers working regular business hours shifts stole sensitive intellectual property from energy companies for as long as four years using relatively unsophisticated intrusion methods in an operation dubbed "Night Dragon," according to a new report from security vendor McAfee.

The oil, gas, and petrochemical companies targeted were hit with technical attacks on their public-facing websites, said Greg Day , director of security strategy. The hackers also used persuasive social-engineering techniques to get key executives in Kazakhstan, Taiwan, Greece, and the U.S. to divulge information.

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The attacks have been linked to China due to the use of Chinese hacking tools commonly seen on underground hacking forums. Further, the attacks appeared to originate from computers on IP (Internet protocol) addresses in Beijing, between 9 a.m. to 5 p.m. local time there, suggesting that the culprits were regular company employees rather than freelance or unprofessional hackers, McAfee said in its report.

Although McAfee said a group of hackers likely executed the attacks, it had pinpointed "one individual" located in Heze City in Shandong Province "who has provided the crucial C&C infrastructure to the attackers."

"It is likely this person is aware or has information that can help identify at least some of the individuals, groups, or organizations responsible for these intrusions," McAfee said. Day said it is routine for McAfee to notify law enforcement in such instances.

McAfee's report is just the latest to underscore the continuing efforts of hackers to steal sensitive corporate information. In late 2009, Google said it had seen attacks believed to come from China, which targeted dozens of other multinational companies, called "Operation Aurora."

McAfee did not publicly identify the companies attacked, but Day said some employed McAfee's professional services consultants.

Writing on a company blog, McAfee's CTO George Kurtz said the attackers used "an elaborate mix of hacking techniques" but methods and tools that were "relatively unsophisticated."

But while seemingly downplaying the hackers' methods, McAfee admitted that it had only recently been able to detect the broad pattern.

"Only through recent analysis and the discovery of common artifacts and evidence correlation have we been able to determine that a dedicated effort has been ongoing for at least two years, and likely as many as four," the report said.

Day said that despite penetration testing designed to ensure a company's IT systems are secure, the breadth and complexity of corporate computer systems has made it increasingly difficult to link malicious actions together.

"I don’t want to say it’s the thing right under the nose that you miss but it's the very reality that things get through due to the depth and scope of the world we have to deal with today," Day said. "We keep seeing all kinds of infiltration because of that challenge."

The attacks often focused on the companies' public-facing websites, which were attacked using methods such as SQL injection, where hackers try to get backend databases to reply to commands that should be blocked. SQL injection attacks can often return sensitive information or allow for different kinds of attacks.

Once a Web server had been compromised, the attackers would then upload programs such as remote administration tools (RATs). Those tools are often used by system administrators to fix computers from afar, as they allow complete access to a machine and let administrators see the system as if they were sitting right in front of it.

From there, the hackers would browse around other areas such as Active Directory, a Microsoft system used to provision network access to employees on corporate networks. They used password-cracking tools to get privileged access to other services on the network containing sensitive information such as market intelligence reports and information on operational production systems, Day said.